System and apparatus employing the hall effect



P. H. CRAIG SYSTEM AND APPARATUS EMPLOYING THE HALL EFFECT Original Filed-Ju1y 9, 1926 2 Sheets-Sheet 1 764C: Source H mv zzvron. BY 2 .4 TTORNEYS.

k, 21, l@. P. H. CRAIG 9 9 SYSTEM AND APPARATUS EMPLOYING THE HALL EFFECT Original Filed July 9, 1926 2 Sheets-Sheet 2 PLWMAA/fA/TMMA/ET 81 a f 62 24 of 9 g -1 7 -30 7o'Zoqd Speaker or lon g Patented Oct. 21,1930

TES

ITED STA PALMER zmrr snare,

SYSTEM PA NT- or Flea I CINCINNATI, OHIO Original application fled July 9, 1926, Serial No. 121,394. Dividedand this application. filed January 14, 1929.-

My invention relates broadly to electrical apparatus for modifying the character of electrical current and more particularly an apparatus for effectively employing the transverse potential difference in certain metallic plates when subjected to theaction of a longitudinal current and the influence of a magnetic field.

This application is a division of my application S. N. 121,394, filed Jul 9, 1926 for system and apparatus employing the Hall effect.

One of the objects of my invention is to provide a device consistingof a plurality of rectangular metallic foil sheets or metallic alloy plates in stacked arrangement insulated one from another and electrically connected in parallel at opposite ends thereof and in series along the transverse axis thereof, whereby current of direct current characteristic may be secured in a circuit which connects to points along the transverse axes of the plates when alternating current is supplied to the opposite end of the plates and a magnetic field created around the plates.

Another object of my invention is to provide a construction of. fixed rectifier for alternating current which remains in permanent adjustment and does not require resetting from timeto time.

Another object of my invention is to provide a device for modifying electrical current of alternating characteristic for rectifymg, amplifying or causing the generation of electrical oscillations of any selected fre-.

will be understood from the specification Serial No. 332,544. 1

hereinafter following by reference tothe accompanying drawings in which:

Figure 1 represents in perspective view the arrangement of parts in the apparatus. of my invention; Fig. 2 is anend view of the apparatus showing more clearly the direction of the magnetic field perpendicular to the plane of the metallic plates; Fig. 3 is a schematic view showing the arrangement of the metallic films which comprise the apparatus of my invention; Fig. 4 is a diagrammatic. view showing the wiring arrangement of the apparatus 0 my invention when used as a rectifier; Fig. 5 shows one of the applications of my invention in a reflexsignaling receiving circuit; Fig. 6 illustrates an application of my invention as a detector in a radio re- .ceiving circuit; Fig. 7 shows a circuit arrangement which makes use of the principles of my invention in the amplification of signal energy, provision being made for facilitating the production of oscillations; Fig. 8 shows a circuit arrangement wherein the longitudinal current which passes through the plates of the apparatus of my invention is derived from a source independent of the source which creates the magnetic field about the plates; Fig. 9, illustrates a circuit arrangement employing a plurality of the devices of my invention as an amplifier of incoming signaling energy and as a rectifier of the amplified energy; and Fig. 10 shows the fundamental arrangement of the magnetic field transverse to the plane of the several metallic films in the apparatus for developing the principles set forth herein.

My invention makes use of the Hall, Corbino and similar electromagnetic phenomena for the rectification or amplification of alternating currents, and the generation of sustained electrical oscillations in electrical circuits.

The Hall effect consists, briefly, of an electromagnetic phenomena observable when a strip or film of metal carrying a longitudinal current I, (Fig. 3) is placed in'a magnetic field perpendicular to the plane of such a strip, a transverse potential difference being set up between the edges a, a, of the strip, this difierence of potential being approximately, under normal conditions, represented by the formula:

E=the traiisverse potential diiterence I=the current (longitudinal) through d=the thickness of the strip.

H=the magnetic field strength. I

The Corbino eifect is similar to the Hall effect, wherein a radial current throu h a circular disc subjected to a magnetic eld perpendicular to the plane of the disc, produces a circular current through the disc.

I have discovered that if plates or films of metal such as bismuth, tellurium, bismuthantimony alloy, or other metal or alloy, be connected as shown in the drawin the device will act as a practical recti er of impressed alternating currents. Referring to the drawings in Fig. 4, the alternating curwhere i the strip rent is sent through the strip 1 from c to d,

in one-half of the cycle, and from d it enters the solenoid S, being an air core or a core of magnetic material, thence after passing through the solenoid it returns to the alternating current source. In the other half of the cycle the operation is, of course, reversed. Fig. 4 also shows the, method of stacking many plates 1, 2 and 3. on top of one another, with suitable insulation between, and then connecting the positive Hall effect potential point ofone plate to the negative Hall efiect potential point of the one below, as represented in the drawings at e, f, g, h,'i and 7'. In other words, the transverse potential of all of the plates 1, 2 and 3 are put in series in order to add up to larger values of potential than would be obtained with a single plate.

It lS 'ObVlO11S, that since the polarity of the Hall effect potential difierence changes in synchronism with either the change in polarityof the points e and d, or with the change in direction of themagnetic flux e, j, Fig.- 4) will always be the same with respect to each other when both the magnetic flux and also the longitudinal current through the plates change in phase and synchronous- Iy with each-other. 'The arrangement shown in Fig. 4 will. then obviouslygive a pulsating direct current at the points 6, r

The construction of the apparatus of my invention is more clearly illustrated in F ig- 1 where the metallic films have been representefl at 1, 2, 3, 4 and 5 separated by insu throu(gh the plate, the polarity of the points been divided into two sections for producing a transverse magnetic field through the metallic films.

In Fig. 3 I have shown a stacked arrangement of metallic films separated by insulated sheets in accordance with my invention, where the alternating currentIpasses along the longitudinal "axes of the films from d to 0. I provide copper end contacts 8 and 9' especially to replace the crystal detector or the triode vacuum tube'detector in radio reception. It could be used either alone or in combination with electron tubes, a typical circuit diagram of the. latter method being given in Fig. 5.

Referring to the drawing in more detail the receiving antenna system is represented at 10 which connects to aground system at 11 with a coupling inductance 12 therein coupled to the tuned input circuit'14: of the electron tube 15 which functions as a radio frequency amplifier. The output of the radio frequency amplification circuit 15 connects through a tuned circuit'16 with the input circuit of a second stage of radio frequency amplification constituted by electron tube 18, the output circuit of which includes transformer system 17 tuned as represented at 28 for supplying exciting current to the solenoid S through a series circuit which passes through the longitudinal axes of the metallic films from points (i to c. A direct current is derived across the pointsv of contact a and a which directly proportional to the incoming signaling energy. The rectified currentis delivered through a trans-. former system 20 to the input circuit of the electron tube 18 which also functions as an ,audio frequency amplification system deliv'ering its audio frequency output through transformer 19 -with..the input circuit of electron tube 15 whichserves also to amplify at audio frequency delivering its output to telephonesT' Battery -A supplies filament heating current for the se'veral'. tubes while battery B. supplies space current for the :tubes. ,.-The;-tuned system 17-28 permits a relatively large value of current to pass through the metallic films and thereby secures maximum direct current energy across the transverse axes of the metallic films. My invention maybe applied to all standard cir-' cuits as well as-as to the reflex system of Referring to Fig. 6 a sim lified circuit is illustrated showing the appiication of the principle of my invention to a simple radio receiving apparatus. In this circult the incoming signaling energy delivered from tuned circuit 14 passes through the longitudinal axes of themetallic films from d to 0 at the same time setting up a magnetic field bymeans of solenoid S for deriving direct current across the transverse axes of the metallic films at a and a proportionate to the incoming signaling energy. This direct current directly actuates the telephone responsive device T. a

It should be noted that, due to the fact that this system is a perfect rectifier (that is, it admits of no inverse potential or currents in the output) it will produceno distortion in the reproduction of radio telephone signals and voice, and is, therefore, far superior to either the crystal detector or the electron tube from the standpoint of faithful reproduction, in addition to its superior qualities of stability, ease of operation and lower cost of maintenance.

Fig. 7 illustrates a circuit arrangement which I employ in the amplification of signaling energy by means of the apparatus of my invention. An input circuit has been illustrated in the form of an inductive coupler 25 tuned by variable condenser 26 and connected through the longitudinal axes of the metallic films at (Z and c. A permanent magnetic field may be established about the metallic films by means of a local source 21 connected in circuit with the winding S. An iron core may be provided for this solenoid S. Incoming signaling energy is supplied through winding 27 coupled with the windings 25. The transverse axes of the films at a and a are connected in series with a local source 22 and an inductance 24 which couples with the inductance system 25. A desired degree'of regenerative amplification is thus introduced for increasing the amplitude of the impulses of signaling energy delivered to the output circuit. The principle of my invention may be applied to an oscillator where the input coil 27 connects to a small local exciter of alternating current and the output connected through a transformer system. By employing selected values of inductance, capacity and resistance the system may be arranged to oscillate at either audio or radio frequencies.

Fig. 8 illustrates a method of obtaining greater energy amplification in the apparatus of my invention. A permanent magnetic flux is set up through the thickness of the plates and also a permanent longitudinal current is established, along the horizontal axes of the plates from a battery 28. A tuned input circuit system 272526 is arranged to excite the winding S which encloses the stack of alternately positioned films and dielectric sheets. The longitudinal axes of the films are connected at points a and a"with an output circuit including a source of potential 22 and inductance 24. The inductance 24 is inductively coupled to an inductance 29 tuned by means of condenser 30 in the out ut circult of the electrical system. The uctuating magnetic field from the winding S which varies in proportion to the amplitude of the signaling energyis superimposed on the permanent fieldwhich is established.

The input may also be superimposed on the longitudinal current instead of upon the magnetic field. The local battery for supplying longitudinal current to the conductive films may thus be eliminated. The local battery in the circuit of the electrical, system is pro- 'vided to boost the voltage of the output to the proper value for the operation of succeeding amplifier stages or the reproducing unit, the Hall fluctuating potential being then superimposed upon this steady potential, By increasing the number of conductive films in parallel the eflfective potential may also be increased.

In Fig. 9 I have shown an application of my invention to an electron tube circuit where the conductive films have their longitudinal axes connected in series in the output circuit of electron tube 15. A constant magnetic field is supplied from battery 21 to the winding S. In this manner the device operates as a radio frequency amplifier, delivering amplified energy to an output circuit across the transverse axes of the conductive films in series as represented at e and j, the output circuit including battery 22 and solenoi dal winding S. The solenoidal winding S connects inseries with the longitudinal axes of conductive films as represented at 0 and d and across the transverse axes at a and a I connect the output circuit which includes the battery 22. The arrangement of the conductive films within the solenoidal winding S serves as a rectifier of amplified energy delivered by the conductive films within the solenoidal winding S.

Fig. 10 shows a method I may employ for setting up the magnetic field which threads through the conductive films. A pair of compressed silicon steel filing core-s or other suitable magnetic material or alloys are arranged on opposite sides of the stack of alternately positioned conductive films and dielectric sheets. On these coils are provided the windings S and S supplied from the local source 21. The stock of bismuth or metallic alloy conductive films may be quite thick but the magnetic field is concentrically normal to the plane of the conductive films. Permanent magnets may also be employed instead of electromagnets. 1

It willbe understood that I may employ conductive films of alloys, metals, crystals or chemical salts in lieu of the bismuth films mentioned herein. Photo-electric materials may be rovided for the films. stances, may produce the bismuth films by cathodic sputtering, thus making the films very thin.

inversely proportional to the thickness of the The transverse current eflfect is film and when the films, which are often so thin as to be transparent to .light, are deposited on thin mica approximately 100 films are connected in series transversely for securing desired operation. The magnetic field in some cases is 1produced by a solenoidal coil of approximate y 1,000 turns on cores of compressed silicon steel filings. The resultant transverse pulsating direct current is several volts for only one milliampere flowing through the field coil and longitudinally through the conductive films in parallel. I have found that where four amperes alternating current at 60 cycle frequency is passed through a 12 turn coil and then through'the conductive films connected in parallel with themselves longitudinally, the resulting pulsating direct current component across each conductive film is approximately -microvolts. When the conductive films in the number above referred to are connected in series transversely 200 micro-volts may be obtained. The values obtainable may readily be used in the operation of electron tubes. The arrangement of the apparatus is such that connections may be readily made with electron tube circuits directly in the input circuit of an electron tube as represented at Fig. '9 without the interposition of transformer systems. 1

When an iron core is used with the device of my invention with the proper permeability curve an asymmetric characteristic curve may be obtained with the device similar to that obtained with a triode tube. This ability of the device of my invention facilitates the generation of self-oscillations in the device. The device when properly connected will, therefore, operate as an amplifier or as an oscillator in addition to its properties as a recti- While have described my invention in J certain preferred embodiments, I desire that it be understood that variousmodific ations may be made without departing from the spirit of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. In a system for generating electrical oscillations the combination of a plurality of conductive films each possessing Hall effect and insulated one from the other, each hav ing longitudinally and transversely extending axes, separate circuits connected in series with sald longltudinally and transversely extending axes, said. circuits being mutually coupled for the generation of electrical oscillations and means for subjecting said conduc- In some intransverse to the plane thereof.

2. signaling system comprising a tuned c rcult a multiplicity of alternately positloned conductive and dielectric films disposed in planes parallel one to the other, said conductive films each possessing Hall effect, means connecting the longitudinal axes of" said films with said tuned circuit, meansfor establishing a magnetic field normal to'the planes of said films and connections across the transverse axes of said films including an inductance element magnetically coupled with a portion of said tuned circuit and con-.

, nected to an output system for regeneratively amplifying incoming signaling current impressed upon said tuned circuit and delivering the same to said output system.

3. Anoscillatory system comprising a multiplicity of alternately positioned conductive and dielectric films disposed in planes parallel one to the other, said conductive films each possessing Hall effect, a tuned circuit for supplying modulated signaling energy to the longitudinal axes of said films, an inductance positioned adjacent said films for establishing-a magnetic field normal to the planes of said films and an output system connected across the transverse axes of said films and coupled with a portion of said tuned input circuit whereby current derived from Hall effect produced in accordance with the modulated signaling energy may be :mplified and delivered to said output sys- 4. -A signal apparatus comprising a multiplicity of alternately positioned conductive and dielectric films each of said conductive films possessing Hall effect, a tuned input circuit, connections for delivering modulated signaling energy to the longitudinal axes of said films, means for establishing a magnetic field normal to the planes of said films, circuits extendingfrom the transverse axes of said films and including a coupled element coupled with a portion of said tuned input circuit and connected with an output PALMER HUNT CRAIG. 

